More Grounding Questions

Thanks Heyraz. Let me provide more info. My main power amp has both AC ground and signal/circuit ground wired to the chassis. One of my sources, SlimDevices Transporter, has both AC ground and signal ground wired to the chassis also. So does my preamp. They don't hum at all.

My secondary power amp had the same setup too but it did hum. The hum stopped after I disconnected the signal ground from the chassis.

My system does not have popping sound nor audible noises from the speakers. I am also an electrical engineer with lots of formal education in EE. But I'd like to learn from others who have practical hands-on experiences with their audio equipment. There are a lot of things in audio gears that school books didn't teach. Or I have forgotten most of them.....

Thanks Heyraz. Let me provide more info. My main power amp has both AC ground and signal/circuit ground wired to the chassis.

I don't think I've ever seen that in audio gear.If someone used a cheater plug that can reverse the neutral,and the hot phase line,that would give 120 volts to the chassis.Zap the user,plus fireworks possible.I can see them tying the green ground to the chassis.I don't think I would experiment either.

Maybe,I'm thinking your reference to the AC ground as the neutral.Hopefully,It has the outlet supply ground tied to the chassis.I'm still thinking,if it isn't broke,don't fix it.

Vett93
This new post of yours has a lot more going on than the original (ground rod placement and ways to minimize noise). And by the way, everything I suggested was from personal practice after consulting EEs and Union Electricians. Being a retail pharmacist has it's advantages, I get to know a lot of knowledgeable people and pick their brains.

Why do you think your secondary power amp hummed when the signal ground was isolated from the chassis?
If I'm reading you correctly, the chassis of your secondary power amp was internally connected to the input signal ground as well as the power ground. When you isolated the input signal ground from chassis (and AC ground), the hum disappeared. How did you do this? If I read you literally, you were able to do this while leaving the AC ground still connected to chassis. I have seen equipment with "ground lifting" switches, but never used one in practice, nor do I fully understand it. Perhaps another reader can explain further.
Have you been able to obtain schematics of your equipment?
Did you open it up to verify that the power was proper polarity with regard to hot and neutral? Have you checked for leakage?
What equipment do you have exactly? Perhaps other readers have had personal experience. I read a post a few weeks back regarding a preamp/poweramp mismatch. Without getting specific, the two were literally oil and water, one passing DC to another unable to handle it. Perhaps your situation is basic design incompatibility.
I'm no EE but I have built a few kits, fixed a few rigs, and can read schematics well enough to trace a circuit.
Please provide more specific information, I'm intrigued.

Hifihvn, yes, AC ground (not AC neutral) is wired to chassis.

Heyraz, there was a ground loop between the preamp and the secondary power amp. (To be clear, I only use one power amp at a time). So it hummed. Then I isolated the signal/circuit ground from the chassis while keeping the AC ground wired to the chassis. The hum stopped because no ground loop is between preamp and the secondary power amp.

I opened up the secondary power amp to disconnect the wiring. I did check the polarity and it was fine. The manufacturer wouldn't give out schematic. But it is a simple KT88 PP amp and is easy to trace.

When I use the main power amp, there is still a ground loop between the preamp and this main power amp. But it does not hum.

Maybe I should re-phrase my questions:
1. Will ground loops degrade sound quality even though it does not hum?
2. When you "float" your power amp, do you float the signal/circuit ground from the chassis or you float AC ground from the chassis?

Thanks all.